Question: Which of the following numbers is a factor of 88? ${4,5,7,10,13}$
Explanation: By definition, a factor of a number will divide evenly into that number. We can start by dividing $88$ by each of our answer choices. $88 \div 4 = 22$ $88 \div 5 = 17\text{ R }3$ $88 \div 7 = 12\text{ R }4$ $88 \div 10 = 8\text{ R }8$ $88 \div 13 = 6\text{ R }10$ The only answer choice that divides into $88$ with no remainder is $4$ $ 22$ $4$ $88$ We can check our answer by looking at the prime factorization of both numbers. Notice that the prime factors of $4$ are contained within the prime factors of $88$ $88 = 2\times2\times2\times11 4 = 2\times2$ Therefore the only factor of $88$ out of our choices is $4$. We can say that $88$ is divisible by $4$.